Title: Isocyanate-Free Single-Component Polysiloxane Topcoats for Surface Ships and Aircraft
Author: Erick Iezzi, Ph.D.
The Naval Research Laboratory (NRL) has recently developed novel isocyanate-free, single-component (1K) (i.e., all-in-one-can) polysiloxane topcoats for use on Navy surface ship topsides and the exterior of Navy aircraft. For ships, the coating is designed as a haze gray colored system that is low in volatile organic compounds (VOCs), free of hazardous air pollutants (HAPs), and provides a semigloss finish. The coating can be brush- or roll-applied by sailors for touch-up and repair applications or spray-applied by contractors during depot-level maintenance. The 1K polysiloxane for ships provides excellent adhesion to a variety of high-solids epoxy primers, enhanced first-line corrosion resistance, greater cleanability compared to qualified silicone alkyds, and has demonstrated excellent color and gloss retention when tested on active surface ships in Norfolk, VA and San Diego, CA. For Navy aircraft, the 1K polysiloxane is designed as a camouflage gray colored system that is HAPs-free, low in VOCs, is spray-applied using high-volume low-pressure (HVLP) equipment, and provides a low-gloss finish. When tested in the laboratory the 1K polysiloxane aircraft topcoat has demonstrated similar performance to qualified polyurethane topcoats, yet unlike polyurethanes these systems are free of toxic isocyanate-based materials.